I don't think that matters much considering the Laser driver regulates the voltage to the LD which is around 5v. There is a few seconds after the LD comes on to the point where it starts engraving with varied power anyway. What are we talking about milliseconds for the power supply to stabilize? Even if that was an issue, a delay can be set in Mach3 for M03 (spindle on) before it starts moving to the start engraving point. I have both my machines set for zero M03 spindle delay and have the 7 second delay disabled on the Flexmod's also.

Hi Robbie, The 10K pot connected to the input pin (2) of the op amp through the 51K resistor is used to set the zero bias of the circuit's output. The 10K connected to the output of the circuit is used to set the max. output voltage to 5.0V.

These two circuits may have some interaction when setting them, so some back and forth adjustments may be needed.

Because a laser diode requires that about .2 to .3 volts be applied to the FlexMod before it starts to lase, the bias setting can be used to set the minimum voltage from the circuit that a specific LD requires to just start to lase (I think mine is set to about .25 volts).

These two adjustments should be made before connecting the circuit to the FlexMod.

Hi Jeff, it's been a while since I played with the diode laser, but if I'm recalling correctly, the 12 volt 6 amp bricks I used to power the twin fans and flexmod on mine took a couple seconds before the fans actually start spinning after turning on the main ac power switch. seems to me that in the original small case, the same applied to the lcd thermometer screen and the fan. From what I've read, laser diodes don't tolerate reverse biasing very well, so any negative going spikes/grass on the +12 volt dc lines would be bad for their health. Been playing with the co2 laser, cutting parts for some engraved music boxes. Thought I had some pix, but can't find where I put them must be another senior moment....

Hi Dave, I'm new to the game so if I'm wrong here go ahead smack me down. I'm sure Jeff is more qualified to answer your comment. But anyway isn't that what the Lasorb is for? Oh and I will be using a PC 350 watt power supply for the fans, DAC, and Flexmod. I have a separate 24 volt power supply for steppers.

Hi Dave, Glad to see you are still hob-nobbing with us "Junior Laser Users." *********************************************** Robbie, Dave designed the earlier DAC circuit for analog control laser diodes from Mach3 that I started with, and suggested using the present MAX chip. Then he moved on to using big-boy lasers. He is more savvy than I am with electronics, and I really appreciate his advice and help.

John I wasn't intending to come off in a bad way. It was one of those answer a question with a question type deals. I have messed with electronics since I was about 5 years old but I can't set down and design a simple circuit much less something like this. Sorry Dave if my comment came of bad.

Yes, the Lasorb protects the laser diode from reverse biasing/spikes. My first build called the mini (same as yours Dave) has two of those 12v 6a brick powers supplies. Remember, I added the second one just to power the fan so it would not slow down when the laser diode throttled up. They both come on in less then a second. It has a Flexmod also and we are going on 1258 hours with no issues or a LD failure.

Dave, yours did not have the 7 second delay enabled either, so what is your point?

On our dual LD machine, we had the LD's fail from over powering them (2.1a each) and from not using the lasorb. We use a Chinese 12v 15a regulated power supply to power two 9mm 445nm LD's, two Flexmods, two 50cfm fans and the temp meter and everything comes on almost instantly

Dave only suggested that particular Maxim chip part number after I suggested a different Maxim digital potentiometer, to be clear.

John, don't cut yourself short. As far as I know, you are the only person that has really made any DAC work properly with an analog modulated LD driver because of your circuit re-designing even to Dave's and our original Maxim DAC.

Larry, Absolutely noting wrong with your posts. I apologize for making you feel as if their was. Jeff, Dave, and I are good friends, and I was just trying to introduce them to you.

Your DAC is looking good. We have another member here putting a DAC system together, too. Maybe the picture of yours will prompt him to start posting soon, too (Larry Z, hint, hint, hint ).

From what I have read, the capacitor now included with the Flexmods is for the output to the laser diode if long leads wires are to be used. I have not verified this yet myself, so perhaps someone else here may know for sure. There was no capacitor supplied with mine, and I will be using about 24" lead wires. I'm glad you mentioned this.

***************************************** "Dave only suggested that particular Maxim chip part number after I suggested a different Maxim digital potentiometer, to be clear. " Sorry Jeff. You are correct. My memory of past events is is about equal to my memory of "future" events.

Jeff he is referring to the 270uf 35 volt that comes with the Flexmod now. It is not in the manual. I asked you about on page 48 toward the bottom of the forum. I haven't figured out how to quote on the forum yet. I think you said "It is not for our use".

Highlight what you want quoted and select quote. I was referring to the beam suppression. I was not sure what you meant about the capacitor. That was a new one on me. I purchased the Flexmods for our dual last year and no capacitors came with them.

That distance is more like 24" on ours too, but if it was an issue, it would have happened by now. That may have been what had taken our our LD's when we did not have the Lasorbs wired in before. We were using the Denmark driver then, not the Flexmods.

Jeff

I paint with two blue beams of light. Extensivly Re-worked/Re-designed/Modified Servo K2CNC KG-3925 and the Mini Laser Engraver

Got two problems. I rechecked my wiring and 3 wires are soldered in the wrong spot. And my heat sink is to small and the hole in it to big. I ordered a new heat sink it is 2 3/8 x 2 3/8 x 1 inches with a copper core. Do you think it will be big enough to provide enough cooling?

Yes, it looks like it will cool it enough, but if you do not drill the hole so it will be a snug fit, it may not transfer the heat properly. Both of my heat sinks are two piece so it clamps the LD housing tight into it. I use the thermal paste also. Both of my machines have a LCD Temp. meter to monitor it while engraving too.

Robbie, That seems pretty close to what I am using now. I think it will be adequate. Just be sure to use some heat sink compound on the diode holder. I made my first heat sink which is about that size, but with no fins and fan. John